diff --git a/lib/asn1/gen.c b/lib/asn1/gen.c
index df3365be7..780444317 100644
--- a/lib/asn1/gen.c
+++ b/lib/asn1/gen.c
@@ -40,8 +40,8 @@ FILE *headerfile, *codefile, *logfile;
 #define STEM "asn1"
 
 static const char *orig_filename;
-static char header[1024];
-static char headerbase[1024] = STEM;
+static char *header;
+static char *headerbase = STEM;
 
 /*
  * list of all IMPORTs
@@ -75,8 +75,8 @@ init_generate (const char *filename, const char *base)
 {
     orig_filename = filename;
     if(base)
-	strcpy(headerbase, base);
-    sprintf(header, "%s.h", headerbase);
+	asprintf(&headerbase, "%s", base);
+    asprintf(&header, "%s.h", headerbase);
     headerfile = fopen (header, "w");
     if (headerfile == NULL)
 	err (1, "open %s", header);